1. Field of the Invention
This invention relates to actuators and actuation systems in general which are extendable for use in the deployment of flexible bodies and similar objects. More particularly, this invention relates to extendible actuator devices constructed of light weight materials having high temperature resistant properties suitable for use in high temperature environments for deploying flexible nozzle extensions of rocket motors and, in addition, are telescopic and self-locking when extended.
In a preferred use for deploying rocket motor nozzle extensions, the actuator has a hollow interior and is extended pneumatically by gas pressure to deploy the extension to which it is attached. Pressure gas is supplied by a gas generator contained interiorly of the device. In its fully extended position, the interior is simultaneously vented of the actuating gas automatically eliminating its added weight.
Briefly, this invention utilizes a plurality of hollow, movable segments, elements or members of the form arranged telescopically with a fixed base member in which a gas generator is housed. Each movable member has a resilient end portion which facilitates telescoping of the members and further features a device in the form of a radially extending projection which engages with another device in the form of a recess in an opposite end of the member to lock the member in its fully extended position and thereby deploy an extendible body such as a folded, flexible nozzle extension on a rocket motor.
2. Description of the Prior Art
Actuators of the class to which the present invention belongs, including telescoping ones, are well known. For example, telescoping pneumatic actuators made of metal have long been fabricated even for rocket motors and nozzle extensions. These devices, however, as typified by the one disclosed in U.S. Pat. No. 3,346,186 tend to be overly heavy and incapable of sustained operation in the high temperature environment (exceeding 5000.degree. F.) of a rocket motor, particularly radiation cooled motors and nozzles. In addition, in this device, self-actuation and self-locking are unknown and venting of actuation gas is neither provided for nor taught and, although pressurization by gas is shown, it is supplied from an outside source such as a pressure fluid container or the like carried on board. Venting of the interior, as mentioned herein is not considered, hence the system of this patent of necessity must be considered as too cumbersome and complex for extensive use in rocket motor nozzle extension deployment systems.
In the non-related art of lawn sprinklers, U.S. Pat. No. 2,614,887 exists which discloses telescoping water conduit sections and which, intended to be extended manually, is provided with internal seal means to prevent water leakage between sections. This device is not, nor is it intended to be used as an actuator, hence it cannot be used to extend deployable bodies as in the present invention, nor is locking of the various sections provided for when extended.
In another patent illustrative of rocket motor actuation devices, U.S. Pat. No. 3,563,467, slidable nozzle covers movable longitudinally of the nozzle by hydraulic actuation means are disclosed. The actuators shown, however, are not telescopic nor is there any suggestion in the disclosure of this patent that the materials of which the devices are made should be selected on the basis of light weight or possession of high temperature resistant properties.
As an illustration and example of high temperature resistant materials, U.S. Pat. No. 3,081,705 is of interest as disclosing a method of making laminated articles by winding strips of resin impregnated material on a mandrel. To the extent that the disclosure of this patent aids in a better understanding of the present invention, its teachings may be found useful and helpful. However, in no way can this patent be construed to disclose or obviate the teachings of the present invention of an actuator for the purpose described.
The present invention, owing to its light weight construction, preferably graphite, its capability for self-locking in extended position, its capability for timely shedding of added weight, such as that of the gases generated to extend the device which are automatically vented overboard and its possession of high temperature resistant properties with strength retention, provides a genuine advance in the art of actuation devices in general and for devices of this kind which are called upon to operate in the high temperature environment of a rocket motor.